ARB drop link lower bush

[ZsZ]

I am just curious what is the difference between the anti roll bar drop link bushes.
There is an early vs late version according to ETKA. Partnrs are 251411039 vs 411513121.
However some aftermarket ones have the partnr as equivalent. Like there is only one powerflex for the 2wd and one for syncro.
From the pics on the internet the early looks thicker. But I had no opportunity to compare them IRL
Does anybody have any info to share?
Thanks!

[Aidan]

must be a stiffness/deformability thing/shore rating, the early arb set up is a little bit different, and interestingly the Syncro uses the early (251) version, with thicker washer plates rather than the golf ones used on the 2wd, the sleeve stays the same
the Powerflex bushes have I think been adjusted over time
I prefer the rubber ones on a Syncro, fortunately I managed to get a few genuine ones before they went obsolete originally